1. Field of the Invention
This invention relates to an image forming apparatus such as, e.g., a printer or photocopier and, more particularly, to an image forming apparatus forming a portion of a medium conveyance route and having a unit detachably attached to an apparatus housing or a unit that can be drawn from the apparatus housing.
2. Description of Related Art
Image forming apparatuses have been disclosed in which images are formed as paper is fed sheet by sheet successively and the paper side is reversed to make the double side of the paper printed. With such an apparatus, to print plural pages, the paper is sequentially and successively supplied, and images are formed on the respective papers as the papers are conveyed parallel in the respective conveyance routes to deliver the paper completed with image formation is delivered at a delivery portion, see, e.g., Japanese Unexamined Patent Publication No. Heisei 11-208,962.
With such an image forming apparatus, paper feeding operation and printing operation are immediately stopped upon recognition of paper jamming occurrences, when plural sensors arranged in the respective conveyance routes detect occurrences of, e.g., feeding defects and doubly feeding, or namely, when paper is not fed for a prescribed period or when the apparatus detects existence of a paper at a certain place for a prescribed period. For example, paper may occasionally stop astride a conveyance route and a reverse conveyance unit during execution of double side printing. If the reverse conveyance unit is drawn out of the apparatus body to remove the jammed paper in such a situation, the paper may be tom or broken up, thereby rending paper removing work laborious and complicated, and thereby raising problems such that it forces delayed recovery and needs a long time to restart printing.